Process of drying lithographed metal plates



Feb. 27, 1923. 1, 1Zef947. T. L. TALIAFERRO PROCESS OF DRYINGLITHOGRAFHED METAL PLATES.

FILED APR. 7, 1920.

avwewboz Patented Feb. 27, 1%23.

entree stares p fi.

THOMAS L. TALiArEImo, or CHICAGO, ILLINOIS, essrsnoa 'rornonmxnn'nmn'rrc COMPANY, or cnroaeo, ILLIN lS, A CORPORATION or nEw YORK."

PROCESS OF DRYING LITHOGRAPHED METAL PLATES.

Application filed April 7, 1920. 4 Serial NO. 372,055.

' useful Improvements in Processes of Drying Lithographed Metal Plates,of which the following is a description, reference being had to theaccompanying drawing and to" the figures of reference marked thereon.

The invention relates to a new and useful improvement in the process ofdrying litho graphed metal plates, and more particularly to metal platessuch as are used in the {ginning of metal containers, covers, orthe Anobject of the invention is to provide a process of drying lithographedplates, whereby the plate may be quickly dried without any discolorationof the pigments of the lithographing ink.

A further Object of the invention isto pro.- vide a process whereby thedrying. of the sheets may be efiected during the continuous travel ofthe sheets. 1

These and other Objects will in part be obvious'and will in part behereinafter more described.

fullyl T e figure of the drawings shows more or.

less diagrammatically a rying oven..'for carrying out my improvedprocess.

Prior to my invention, it has been -common to decorate metal sheets withink by various lithographing processes, and then the sheets are dried.This drying of a lit'hographcd sheet has been accomplished by sub---jecting the sheet tov a low heat fora considerable period of time, andthis was thought necessary in order toprevent the discoloration of thepigments -.contained in the ink. It is well known that the drying ofa'lithograph ink is not a volatilization' process, but,

on the contrary, is'a chemical actlomvthe ingredients oxidizing and thusbringing about a settingor drying of the ink. This oxidationprocess,whiol1 results in the drying of the ink is therefore aprogressive or. cumulative actionf andgtlmeis' required in. orderto-efiectthe same; I have discovered that a lithographed sheet of metalmaybe heated to relatively high temperature so as toincr'ease'therapidity of the chemical action, and the resulting drying of the; inkprovided that .thisintense heat to which the ink is subjected,isrestricted to a veryshort the pigments.

tion described in detail in my interval of time. The discloration of thepigments due to heat, is not rapid, but Occurs only after the lithographink has been subjected to a relatively high temperature for a relativelylong period of time; My improved process of drying lithographed platesconsists therefore in the heating of the lithographed sheet to acomparatively high temperature so as to bring about a rapid oxidation ofthe ink and the resulting drying thereof and the restricting of theheatperiod withdrawn from the heating chamber and allowed to quicklycool.

Another Object of my process consists in the passing I of the sheetscontinuously through a heating chamber wherein the sheet will be quicklyraised to the tempera ture referred to above, and the withdrawing of thesheet from the heatin chamber at the end. of the period referre toabove, and preferably maintaining the sheets in vertical position whilethey are passing through said heatin chamber and for a period of timeafter t ey leave the'heating chamber.- This not only causes the sheet tobe quickly heated, to a temperaturewhich brings about'the rapidoxidation of the ingredients of the ink, but it also quickly cools the'sheetland thus preventsthe high temperature effects. upon the ink fromcausing discoloration-of .75 vided the sheet is at the end of theheating 1 In the drawings l have shown one-form) of apparatus foroarrying out the process, and brief reference will be made thereto. Thedrying Oven is indicated at l in the drawings and is preferably of theconstruc- Patent #1318487, granted October 7, 1919. Passin "through theOven is an endless conveyor 2 iaving vertically extending arms 3 betweenwhich the. jsh'eets are placed. The,

"endless conveyor is driven in any suitable way and the: sheets are fedbetween'the arms by the feeding-in conveyor 4. I have indicated in thedrawings the sheets at S.

The drying chamber is heated as shown in the drawings by gas burners 5which are of such a character that the interior 'of the oven may bemaintained at a temperature from two hundred and fifty to four hundredand fifty degrees. At the upper part of the chamber there is alongitudinally extending pipe 6 having openings, and air is supplied tothis pipe and allowed to pass into the chamber. The amount of air thusdelivered to the chamber is comparatively slight and is mainly for thepurpose for causing a. movement of the air within the heating oven so asto bring about a uniform distribution. of the heat in-the oven thusavoidin hot spots and insuring uniformdrying 0% the sheets. At thereceiving end of the oven there is a pipe 7 which is provided withopenings, and this ipe is connected with a suitable supply of air whichcauses the blanket of air indicated by the lines 8 to be formed at theentrance of the oven. This blanket of air serves as a. door for closingthe oven, so as-to maintain the heat in the oven. The sheets, however,will readily pass through the blanket. At the delivery end of the oventhere is another pipe 9 which forms a blanket of air 10 for closing thedelivery end of the oven. Throu h these air blankets, the oven issubstantia y closed so that it may be maintained at a relatively highheat between two hundred and fifty and four hundred and fifty degreesthroughout the entire extent ofthe oven. Through this arrangement, thelithographed sheet is subjected to this intense heat just as soon as itenters the oven and the intense heat continues until the sheet passesthe blanket at the end of the oven out into the open atmosphere. Throughthe subjecting of the lithographed sheets to this high temperature, avery rapid oxidation of the ink takes place. The lengthof the oven andthe speed of travel of the conveyor is such that the sheet will be fromfour to five minutes in passing. through the oven, and therefore,

the drying process which is brought about through the oxidation of'theingredients of the ink will be substantially efl'ected when the sheetleaves the drying oven. By arranging the sheets vertically the surfaceof the ink is directly subjected to the circulating heated air in theoven, and is therefore more quickly brought to the maximum. temperatureof the oven. On the othef-hand as soon as the sheets passout of theoven, the vertical arrangement thereof in the open atmosphere bringsabout a rapid cooling of the metal and the ink, this withdraws the heatfrom the metal sheet andthe ink and prevents the discoloration of thepigments which might result from the heat held in the metal if the metalwas not rapidly cooled.

Through the process described above, it will be apparent that I am ableto very quickly bring the lithographed ink to a teinperature where. theoxidation is ver rapid, maintain it for a short interval at t istemperature, and then quickly cool the same, and therefore the drying ofthe sheet is very much more quickly efi'ected, and without any injuriousresults, such as discoloration f the pigments.

The apparatus which has been described in brief above, forms no partbroadly of the present invention, but is described and claimed in myPatent No. 1,399,415, granted Dec. 6, 1921. I

I have described the above apparatus for the purpose of makingmore clearthe process.- It is obvious that the apparatus for carrying out theprocess may be widely varied. It is also obvious that the specified.temperatures, and the time interval to which the sheet .of metal issubjected to the temperature stated, may be variedwithin suitableranges. the period of time stated are those preferred.

The temperatures and The 'essential feature of the invention consistshowever, in the heating of thesheet to a relatively highltemperature forproducing rapid oxidation of the ingredients of the lithograph ink andrestricting the period of heating so as .to prevent discoloration of thepigments, and this is greatly aided by the rapid cooling of thesheet-after the heat- 1 ing period. v

It is obvious that minor changes in the details of construction ma bemade without departing fromthe spirit of theinvention as set forth inthe appended claims. 1

, Having thus described the invention,what

I claim as new and desire to'secure by Letters-Patent, is':

1. The' process of treating lithographed plates consisting in'travelling the sheet through a drying oven heated to a relatively hightemperature which would, if the operation be continued, carry theoxidization of the ingredients to a point ofdiscoloration of thepigments of the ink, and wherein the airis continuously moving so as toprevent hot spots and to produce a uniform rapid oxidization of theingredients for drying the the end thereof so as to preventdiscoloration of the pigments of the ink.

3. The process of drying lithographed plates consisting in travellingthe lithographed sheets in succession through a drying oven heated to atemperature of two hundred and fifty to four hundred and fifty degrees,the speed of travel being such as to subject the sheets to the heat ofthe oven for a period of between four and five minutes and rapidlycooling the sheet after it leaves the oven.

4. The process of drying lithographed plates consisting in travellingthe lithographed sheets in succession through a drying oven heated to atemperature of two hundred and fifty to four hundred and fifty degrees,the speed of travel being such as to subject the sheets to the heat ofthe oven for a period of between four and five minutes and rapidlycooling the sheet after it leaves the oven, and closing the receivingand delivering ends of the oven by a blanket of air and causing acirculation of the air within the oven so as to bring about asubstantially uniform temperature from one end to the other of the oven.

5. The process of drying lithographed plates consisting in travellingthe sheets in vertical position through a drying oven heated to atemperature between two hundred and fifty and four hundred and fiftydegrees, regulating the speed of travel of the sheet so that each sheetwill be retained in the oven from a period of four to five minutes, andmaintaining the sheets in vertical position in the open air afterleaving the oven until the sheets are cooled.

6. The process of drying lithographed plates consisting in travellingthe sheets in vertical position through a drying oven heated to atemperature between two hundred and fiftyvand four hundred and fiftydegrees, regulating the speed of travel of the sheet so that each sheetwill be retained in the oven from a period of four to five minutes andmaintaining the sheets in vertical position in the open air afterleaving the oven until the sheets are cooled, closing the receiving anddelivering ends of the oven by a blanket of air and circulating the airwithin the oven so as to maintain substantially a uniform temperaturefrom one end to the other thereof.

In testimony whereof, I aflix my signature.

THOMAS LUCIEN TALIAFERRO.

